Posted in Education, Physical Chemistry, Science Education, Spectroscopy, UV-VIS-NIR, working problems

Spectrum of a Particle in a 1D Box

It is safe to say that every physical chemistry course teaches the Particle in a Box problem as an introduction to quantum mechanics. I have taught it also in my course for years.

I have been bothered for years, however, by the fact that the text books stop after solving the Schrodinger equation. All of them that we have surveyed do this. McQuarrie, Atkins, Engel, Levine, etc.

This is a shame because we can’t detect the energy levels by themselves. Quantum theory was invented to explain spectroscopy. So why not take the 1D Particle in a Box (1DPB) problem all the way to a simulated spectrum?

At SHSU, we do.

Here are three lectures that explain what I do with the Particle in a Box.

(Be patient with the Kahoot quizzes and end of class Q&A. Feel free to skip ahead, or try to answer the questions in your own mind to see how you do! To find all my Kahoot content search for my username chem_prof on Kahoot. I have Quantum, Thermo, and Forensic Chem Kahoots.)

Lecture 1 – Managing the Messy Mathematics

This lecture takes the spectrum of a 1DPB apart to show what pieces of the spectrum are explained by quantum theory.

TN-L3

Lecture 2 – The Schrodinger Equation

This lecture is the traditional presentation of the 1DPB problem – normalizing the wave functions and solving for the energies via the Schrodinger equation.

TN-L4

Lecture 3 – Spectral Transitions and Spectral Assignments

This lecture discusses spectral transitions, the transition moment integrals and the transition equation which tells us about the spacing of our spectral lines. The transition equation also tells us about the quantum system if we begin with an experimental spectrum and assign the quantum transitions.

clip-spectral-assignment

What are your reactions to this approach? I’d love to hear from you in the comments section. I am preparing this material for a book for students to read in the summer prior to taking pchem. I think it will greatly help to get them thinking about our quantum world early and often.

Happy Pchemming!

Darren Williams

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Posted in Education, Physical Chemistry, reading science, Science Education, working problems

How to Teach Yourself

How do you teach yourself a new skill? How do you learn a tough subject? (like pchem?) I’m glad you asked. Here are my tips and tricks specifically focused on pchem survival (but applicable to life in general).

problems-notebook-cropped

1. Don’t be afraid! (and that’s an order!)

Thousands have been down this road and they were in your shoes back then. You may have to shore up some mathematical deficiencies and look up some vocabulary, but these tasks are obvious to you as you go along. None of this affects your value as a person. But do you have the drive to re-learn what you have forgotten and dig into what you don’t know yet? Decide now! This is not a technical question. It is a heart question. Your answer to this question will determine your future as a productive team member after graduation.

2. Do the tutorials.

Every book has example problems in the text. Every coding site has tutorials. Even Excel has example data sets in its help files to show you “how it is done”. Do the tutorials.

3. Read the text with a pencil NOT a highlighter.

Write in your book margins. Rework math proofs in your problems notebook. Unless the material goes in your eyes, rattles around in your brain, filters down your arm, and out through your pencil, then you haven’t comprehended the material. Highlighting is nothing but self-deceptive Arts and Crafts.

4. Keep a problems notebook.

Do all your problems in a composition book. It is bound and sturdy. It will last much longer than a spiral notebook. Thirty years from now, you can be amazed at how bad-a$$ you were in college when you look at the math problems you did!

AND you can use it to shame your college-aged kids when they complain that their college prof won’t just upload the homework concepts directly into their brain-chip.

5. UNITS!

If you would just use UNITS on your numbers you would catch 99% of your errors. I can’t scream this loudly enough! Units, units, UNITS! Use them, or fail. It’s on you.

“But they take up space. They take time. Whaa Whaa Whaaaa” Look at the photo uploaded with this post. There is NO way to catch all the powers of 10 that jump around in that problem without using units.

6. Pro-tip: Be Disciplined

“The scheduled task gets done”, said my father.

If your homework time is not scheduled, then it will not get done. If you are not using the phrase, “I can’t, I have PHCEM homework to do.” Then you are not learning pchem.

If you want to learn piano or guitar and you don’t schedule practice time, then I don’t want to hear you play. It is the same with sports. If you don’t schedule practices, then I’m not buying a ticket to your game.

Put LEARNING on the calendar, not just TESTING.

—Here endeth the lesson.